Choosing a format decides how small your image can get and whether it keeps transparency. Here is the practical difference.
The one-line summary
- JPG (JPEG) — lossy, best for photos, universally supported, no transparency.
- PNG — lossless, best for graphics, logos and transparency, largest files.
- WebP — modern, smallest at equal quality, supports both lossy compression and transparency.
Side-by-side
| JPG | PNG | WebP | |
|---|---|---|---|
| Compression | Lossy | Lossless | Lossy or lossless |
| Relative size (photo) | Baseline | Much larger | ~25–35% smaller than JPG |
| Transparency | No | Yes | Yes |
| Best for | Photos | Graphics, logos, transparency | Photos + graphics, smallest size |
| Hits small KB targets | Yes | No | Yes |
| Compatibility | Universal | Universal | All modern browsers |
Why PNG can’t hit small sizes
PNG is lossless — it never throws away detail, so its encoder has no quality dial. The only way to shrink a PNG is to reduce its pixel dimensions. That is why a “compress PNG to 20 KB” request usually means converting the photo to JPG or WebP behind the scenes. FitToKB does this automatically when you set a small target on a PNG.
Which should you choose?
- A photo for the web or a form → JPG (compatible) or WebP (smallest).
- A logo, icon, screenshot or chart → PNG, or WebP if you want it smaller.
- Anything needing transparency at a small size → WebP.
When a form dictates the format, follow it. Otherwise, default to WebP for size and JPG for compatibility.